The present invention is generally directed to the art of solid phase welding or pressure welding of pipes and the like. This general type of process is disclosed and described in U.S. Pat. No. Re. 28,190 of Oct. 8, 1974. In performing solid phase welding to join pipe sections together, the usual practice of supplying the heat to raise the temperature of the pipe end to sub-fusion and fusion conditions is by means of external burners. Such burners, which may be placed around the periphery of the joint, direct, for example, oxy-acetylene flames toward the exposed or outer end portions of the pipe sections. However, the normally hidden or inner end portions of the pipe sections are not in direct contact with the flames, but instead are effectively exposed to the ambient atmosphere.
Accordingly, during the heating process, undesirable and deleterious oxides will form along the inner abutting edges of the walls of the pipe sections. It might be explained at this time that while reference is being primarily made in this application to welding of pipe wherein the problem is particularly acute, the concepts of this invention are also applicable when solid phase welding any objects in which flame heating is applied only from one side or surface of the thickness of sections being joined, while the other side or surface is exposed to the atmosphere.